Heat exchange unit



Aug. 30, 1949. SHAW HAL 2,480,675

HEAT EXCHANGE UNIT Filed 00 i. 29, 1943 5 Sheets-Shet I Aug. 30, 1949. J. c. SHAW ET AL HEAT EXCHANGE UNIT 5 Sheets-Sheet? Filed Oct. 29. 1945 J. C. SHAW ETAL Aug. 30', 1949 HEAT EXCHANGE UNIT 5 Sheets-Sheet 3 Filed 0Ct. 29, 1943 Qir 1 I11. W .1 IIIIIIIFIJIIIIII Aug. 30, 1949. J. c. SHAW ETAL HEAT EXCHANGE UNI T 5 Sheets-Sheet 4 Filed Oct. 29, 1945 J. C. SHAW ETAL 5 Sheets- -Sheet 5 Filed Oct. 29, 1945 i O w w Patented Au 30, 1949 OFFICE HEAT EXCHANGE UNIT Joe 0. Shaw and William Wis., assignors to Your:

J. Schlapman, Racine, g Radiator Company, a

corporation of Wisconsin Application October 29, 1943, Serial No. 508,104 3 Claims. (Cl. 257-128) This invention relates to a heat exchange unit where the heat exchange between a cooling medium and la coolant is efiected by passing the cooling medium through a bundle of tubes around and between which is formed a core for the circulation of the coolant. More particularly, this invention relates to a heat exchange unit for aircraft engines where the cooling medium is air forced through thetubes and the coolant is lubricating oil circulated through the engine. Even more specifically, the invention relates to special improvements in the construction and arrangement of heat exchange devices of the type which comprises a cylindrical casing housing a bundle of cylindrical tubes whose hexagonal expanded ends space the tubes apart throughout almost their entire length and permit the bonding together of the ends so as to constitute the space between the tubes into a sealed core through which the oil circulates.

In modern aircraft, it is essential to superior operation of the engine to keep the lubricating oil as nearly as possible at a uniform temperature. Such uniform temperature must be maintained regardless of the extremely varying temperatures around and above the earths surface where aircraft are used. The possibility of accomplishing that uniform temperature demands a cooling device wherein the degree of heat exchange exposure of the cooling medium and the coolant may be varied so as to compensate for the over-all conditions of weather and engine operation.

The main objects of this invention, therefore, are to provide an improved heat exchange unit of the type herein designated providing the highest possible degree of heat exchange exposure of the cooling medium and the coolant; to provide an improved construction of a warm-up chamber in the middle area of the unit; to provide an improved spacing arrangement of the air-flow tubes at strategic portions of the unit so as to accelerate the influence of the heat from the oil in the warm-up chamber when it tends to become congealed or highly viscous in the area surrounding the air flow tubes; to provide an improved construction of a heat exchange unit of this type which permits a more efiective and economic manufacture of the several parts,

which insures a more facile and efiicient operation of the unit, and which has a greater capacity and durability than heat exchange units of this type heretofore provided. v

In the particular embodiment of this invention herein shown:

Fig. 1 is a front elevation of the improved structure. The figure details only a portion of the tubes which fill the entire space within the shell;

Fig. 2 is a plan view illustrating the arrangement of the ports and channels through which the flow of oil into and out of the heat exchange unit is directed under the influence of appropriate valve mechanism;

Fig. 3 is a side elevation showing, in dotted outline throughout the greater portion of the riew, the interior arrangement of the tubes of ,he warm-up chamber and the bafiie plates. A portion of the figure is broken away at the lower right hand corner to illustrate how provision is made for communication between the bottom of ;he warm-up chamber and the core surrounding the adjacent air-flow tubes;

Fig. 4 is an enlarged fragmentary cross-sectional view taken on the line 4-4 of Fig. 1;

Fig. 5 is a similar view taken on the line 5-5 of Fig. 1;

Fig. 6 is an enlarged fragmentary-transverse view taken on the line 6-6 of Fig. 1;

Fig. 7 is likewise an enlarged cross-sectional view taken on the line 'l-l of Fig. 6;

Fig. 8 is an enlarged fragmentary view taken on the line 8-8 of Fig. 3;

' Fig. 9 is a plan view of one of the corrugated baflle plates such as used in the assembly shown in Fig. 10;

Fig. 10 is a view similar to Fig. 1 showing the use of corrugated baflie plates other than flat plates, as used in the structure shown in Fig. 1; and

Fig. 11 is a plan view of one of the fiat .baiile plates.

In the particular embodiment of this invention shown in these several views, a supporting shell or housing 9 is provided with a middle axiallydisposed warm-up chamber In upon opposite sides of which are arranged symmetrically formed complementary heat exchange sections H. These several parts are so arranged so that there is intercommunication between the warmup chamber and the cores of the sections II and between channels and ports formed in the valve base 12 whereby a valve mechanism (not shown) may regulate the relative flow of oil through the warm-up chamber and the cores of the heat exchange sections II in the passage of the 011 betweerrthe engine and oil supply tank.

The shell 9, as will be observed, is a single piece of sheet metal having the ends welded together as shown at I3 so as to form a cylindriseries of tubes it with which are associated the baiile-supporting bars I], and the end plates or closures l8 (see Figs. 6 and 7).

The headers 15 are secured, preferably by silver soldering, to the inner surface of the shell 9 at diametrically opposite points and between which are positioned the tubes l6 and the end plates or closures IS. The baflie-supporting bars 11 are spanned between and secured to the end practice of assembling the tubes 23 in the shell is a tremendous advantage in manufacture.

plates or closures l8. These headers, as is more clearly shown in .Fig. 8, are of arcuate cross section, but have their ends expanded to a polygonal form. Openings l9 are formed in the sides of the lower header 15 at one end to provvide communication between the warm-up chamber l and the adjacent portion of the cores of the tube sections H, as will be more clearly hereinafter pointed out. Auxiliary openings l9.l (see Fig. 3) are similarly arranged at the opposite end of the lower header 15.

The tubes l6 are of elliptical cross-section. In this embodiment six of them are aligned axially of the shell in the direction of their greatest dimension. The ends of these tubes are inserted through suitable openings in the headers l and are preferably silver soldered thereto. These tubes iii are also inserted through suitable openings in the bathe-supporting bars l1, and may or may not be silver-soldered thereto. The bars I! are of U-shaped cross section and at their ends are silver-soldered to the end plates or closures l8. Ports 20 are formed in the lower ends of the first two (viewing Fig. 3 from the right) of the tubes iii to afford communication between these two tubes and the adjacent portion of the cores of the tube sections II in advance of the communication provided through the ports or openings 19 in the lower head 15. The combined area. of the openings l9 and 20 should be substantially equal to the combined area of the first three tubes l6. At other points the tubes [6 have orifices 2| formed therein registering with enlargements in the core of the sections II as will be more fully hereinafter pointed out.

A partition 22 (see Fig. 3) is formed in the upper header so as to separate the six tubes at their upper ends into two batteries of three each. This partition 22 is related to compartments in the valve base l2, as will be more clearly hereinafter pointed out, so that the three tubes IE to the right of Fig. 3 constitute a battery for the inflow of oil and the three tubes to the left constitute an outflow battery. The travel of the oil is indicated by dotted singleheaded arrows.

Each air-flow heat exchange section H in general comprises the conventional arrangement of tubes 23 for this-type of heat exchange unit. Each section is made. up in a jig. The jigs are symmetrical anad complement each other so that the sections Ii when finished are complementary symmetrical pairs, any two of which will fit in any previously constructed shell. Such forming of the sections as compared with the former As is generally practiced-in the manufacture of this type of heat exchange units, the cylindrical tubes 23 have their ends expanded hexagonally so that a bundle of them may be assembled within almost any perimetric boundary. The hexagonal heads hold the tubes in spaced relationship thus forming a core around and between the tubes. The ends of these hexagonal enlargements are bonded together so as to seal the core within which oil may be circulated for exposing it to the heat exchange effected by forcing air through the tubes 23.

As is customary in this type of structure a series of baflle plates 24 are interposed at intervals and adjacent plates are provided with suitable openings NJ, at opposite axial ends so as to cause the oil to follow a circuitous path in its passage through the core, as indicated by the double-headed dotted arrows shown in Fig. 3. These baflie plates also have orifices 24.2 (as shown in Figs. 4 and 9) formed in the middle area and the end opposite the main opening 241. The orifices permit a trickling through of the inflowing warmer oil from the under side of the baffle plates to the enlarged core space directly above the baffle plates. Figure 1 shows how the angled end flanges on the baflle plates 24 rest against the inner face of the shell 9. Figure 8 shows how the opposite end flanges engage the supporting cross-bars H.

The battle plates 24 may be either flat, as shown in Figs. 1 and 11, or corrugated, as indicated in Figs. 9 and 10. When flat bafile plates are used the air tubes 23 adjacent the bafiie plates require pentagonal-formed ends, as shown in Fig. 1, rather than hexagonal ends, as shown throughout the remainder of the assembly. Moreover, the tubes formed for use adjacent to the flat baflle plates may preferably have the pentagonal heads eccentrically positioned relative to the cylindrical parts of the air-flow tubes. This insures having the cylindrical portions spaced out of contact with the baflle plates.

When the corrugated bafile plates are used the hexagonal ends fit in the corrugations as shown in Fig. 10, and the air flow tubes are uniform throughout the assembly.

Another of the principal features of this invention involves the special spacing of the tubes adjacent to the baflle plates 24 and also the special spacing of a row of tubes intermediate the baffle plates, together with the omission of an occasional tube on the row of specially spaced tubes.

The special spacing of the tubes adjacent .to the bafiie plates 24 is accomplished by fixing a strip of metal 26 along upper edges of the baiiie plates 24 (see especially Fig. 4) so that the adjacent above row of tubes is spaced away from the baliie plates a greater distance than would otherwise be accomplished without the spacing strips 26.

The special spacing of a row of tubes 23 intermediate the baffle plates 24 is accomplished by inserting corrugated strips 21 (Fig. 4) between the enlarged hexagonal heads of adjacent rows of tubes. This provides spaces 28 on opposite sides of an intermediate row of tubes somewhat greater than the space provided between the rows of tubes otherwise throughout the sections ii. Such an enlargement of the space transversely across the sections vll at several levels tends to facilitate the flushing of the congealed or highly viscous oil in those portions of the core as the warm and less viscous oil tends to trickle from the warm-up chamber I0 into adjacent portions of the core of the sections II. In order to facilitate this flushing action in these enlarged core areas, the orifices 2|, in the tubes it of the warm-up chamber III, register with the adjacent ends of this enlarged spacing.

In the rows of increasingly-spaced tubes 23 one or more of the tubes is omitted at a certain point intermediate the warm-up chamber III and the shell 9. The opening is closed by a plug 28 so as to complete the sealing of the core. This occaslonal omission of a tube further helps to accelerate the flushing of the congealed or highly viscous oil from the core of the sections II under the circumstances above mentioned.

The valve base I2 is suitably secured, preferably by silver soldering, to the shell 9 in alignment with the warm-up chamber I0. Studbolts 30 are set in the base to provide for the attachment of a suitable valve mechanism such, for example, as shown in the co-pending application, Ser. No. 510,336, filed November 15,1943, patented June 26, 1945, No. 2,379,109, of Joe C. Shaw.

This valve base I2 has formed therein partitions 3| and 32 (see Figs. 2 and 3) which form chambers 33, 34, and which communicate with the inlet port 38 and the outlet ports 31 and 2-8respectively. These partitions 3| and 32 are so arranged that the chambers 33 and 34 register with the upper header I5 on opposite sides of the partition 22 whereas the chambers 35 communicate with the upper ends of the cores of the sections I I on opposite sides of the contiguous header I5, at the left hand end of the casing 9 as view from Fig. 3.

The end platesv I 8, in the form of channel members, are essential to complete the sealing of the core sections I I around the warm-up chamber III, as will be most particularly noted from Fig. 6. These channel members extend from one of the headers I 5 to the other and, as shown, may even engage the adjacent tubes I6. In order to provide for an accurate sealing of the enlarged ends of the tubes 23 along the members It alternate tubes have a cross-sectional form as shown at 39 of Figs. 1 and 7.

One of the incidental advantages of this arrangement of the warm-up chamber is the provision of the area 40 (see Figs. 6 and 7), vertically and transversely around the tubes I 3 and connecting the cores of the two sections II. The oil which congeals or becomes highly viscousin these areas is exposed to the heat of the oil as it begins to flow through the warm-up chamber I0 and is more readily converted into less viscous condition so as to coact with the enlarged spacing between the rows of tubes intermediate the baflie plates 24 and above the bailie plates to accelerate the flushing of the core in the two sections II.

In explaining the operation of the device herein shown, when used with the lubricating oil system for an aircraft engine, it will be understood that a suitable valve mechanism, similar to thatshown in the aforementioned copending application, would be provided to control the flow of oil through the inlet port 36 and out of one or the other of the outlet ports 31 and 38.

When the temperature of the oil entering the valve mechanism is suiilcient to cause the thermostat to open communication to the port 33, oil would begin to flow in the direction of the single headed arrows shown in Figs. 2 and 3. This now of oil would .pass downwardly through the in- 6 flow battery of tubes I3, of the warm-up chain ber III, through the lower header I5 upwardly through the out-flow battery of tubes It to the upper header I5 and out through the outlet port 5 II, as indicated by the dotted single-headed arrows in Figs. 2 and 3. v

It is assumed that the oil in the communicating cores of the tubular sections II is too nearly congealed or too viscous to flow when communication is iirst opened through the inlet port 36.

That means that the only outlet is from the port 31.

The warm oil passing downwardly and upwardly through the tubes of the warm-up chamher I 3 will first tend to warm up and reduce the viscosity of the oil in the space 40 around the elliptical tubes I8. Also, the oil will tend to trickle out through the openings 2| into the horizontally enlarged portions of the core on opposite sides of the rows of tubes 23 intermediate the baiile plates 24. As the congealed or highly viscous oil in the enlarged horizontal areas of the core continues to warm up, it will soon reach the congealed or highly viscous oil in the space where the tubes are omitted.

' This trickling of the oil horizontally and axially through these enlarged core spaces will tend to accelerate the lowering of the viscosity of the oil in other portions of the core of the sections II preparatory to securing a movement of the oil through these cores as soon as the valve mechanism acts to open the outlet port 38. This will occur as soon as the temperature of the oil passing out through the port 31 to the valve mechanism affects the thermostatic control of the valve suflioiently to further actuate the valve mechanism. The opening of the outlet port 33 means the simultaneous closing of the outlet port 31. Thereupon, oil entering through the right hand battery of tubes I3 of the warm-up chamber III will flow out through the lower header openings I 9 and the openings 23 in the lower ends of the tubes I3. This warmer oil then entering the lower portions oi the cores of the tubular sections II will begin to move up through the lowermost portions of these sections. The lowermost baflle plates 24 will deflect this flow axially toward one end of the shell 3. Inasmuch as the next adjacent baifle plate 24 will have its openings 24.I at the opposite endfrom the lowermost baflle plate oil in the portions between the two lowermost baflle plates will be directly axially toward the opposite end of the shell 9. Because adjacent plates have these openings 24.I at opposite 56 ends, the flow of oil will follow a circuitous path through the unit, as indicated by the doubleheaded arrows in Fig. 3.

When this oil begins to flow out through the openings it into the lowermost portion of the 60 tubular sections II the rising oil striking against the baiile plates 24 will be permitted to trickle through the orifices 24.2 into the enlarged core areas immediately above the baflle plate. Here, again, this will tend to facilitate the reducing 06 of the viscosity of the oil in the adjacent portions of the core and help to accelerate the flushing of any highly viscous oil remaining in the core in the sections I I.

Such a structure, providing these series of enlargements in the core areas oi the tubular sections II along and intermediate the baflie plates, tends to increase very greatly the efliciency of this heat exchange device over previous structures oi this type. With this structure it is possible to secure a more sensitive and accelerated action in the heat exchange (1) between the air passing through the tubes and the oil circulating in the surrounding cores and (2) between oil in the warm-up chamber and the cores of the tubular sections Ii. This makes possible securing a quicker and closer manipulation of the valve mechanism under the action of the thermostat as influenced by the oil passing through the unit. This is especially beneficial when it is necessary to start up the cooling system in the lower temperature conditions and when the aircraft has to alternate between the high temperature at the earths surface and the low temperature of the stratosphere.

Variations and modifications in the details of structure and arrangement of the parts may be resorted to within the spirit and coverage of the appended claims.

We claim:

1. In a heat-exchange unit of the class described, the combination of a supporting shell having an inlet and two separate outlet ports, conduit means providing an axially-disposed fiuid flow path extending transversely across said shell and dividing said shell into two compartments, said conduit means communicating at one end with said shell inlet port and at the other end with one of said shell outlet ports, tubes extending axially of said shell and filling each of said compartments, said tubes having their ends supported in bonded relationship so as to form a sealed fluid core surrounding said tubes in each of said compartments, said cores communicating with the other of said shell outlet ports and with said transverse chamber at a point intermediate said inlet and said'one outlet port, baiile means associated with said axially-disposed tubes in each of said compartments for causing a backand-forth fluid fiow through said fluid cores axially of said shell between the communication of said cores with said transverse conduit means and said other shell outlet port, and other means forming an extra spacing of an occasional row of said axially-disposed core-forming tubes extending from said transversely-disposed conduit means to the periphery of said shell thereby providing occasional enlargements of said fluid cores disposed axially of said shell parallel to said battle means, the conduit means forming said axiallydisposed fiuid flow path having apertures formed therein in registration with said occasional core enlargements whereby fluid from said conduit means is admitted directly to said fluid core enlargements.

2. In a heat-exchange unit of the class de- 65 scribed, the combination of a supporting shell having an inlet and two separate outlet ports,

conduit means providing an axially-disposed fluid flow path extending transversely across said shell and dividing said shell into two compartments, said conduit means communicating at one end with said shell inlet port and at the other end with one of said shell outlet ports, tubes extending axially of said shell and filling each of said compartments, said tubes having their ends supported in bonded relationship so as to form a sealed fiuid core surrounding said tubes in each of said compartments, said cores communicating with the other of said shell outlet ports and with said transverse conduit means at a point intermediate said inlet and said one outlet port, baffle means associated with said axially-disposed tubes in each of said compartments for causing a backand-i'orth fluid flow through said fluid cores axially oi said shell between the communication of said cores with said transverse conduit means and said other shell outlet port, spacing strips along the ends of certain of said babies extending from said conduit means to the periphery of said 5 shell for spacing the contiguous row of axiallydisposed core-forming tubes away from said bailies a distance greater than the normal spacing of said tubes to form core enlargements, and other means forming an extra spacing of an occasional row of said axially-disposed core-forming tubes intermediate certain of said baflle means extending from said conduit means to said periphery, said extra spacing strips and said other conduit means providing occasional enlargements of said fluid cores disposed axially of said shell parallel to said baille conduit means, the means forming said axially-disposed fluid new path having apertures formed therein in registration with said core enlargements along said baiiles and said intermediate row of tubes whereby fluid from said conduit means is admitted directly to said fluid core enlargements.

3. A heat exchange unit of the class described comprising a supporting-shell, means defining a warm-up chamber, baflle means arranged in said shell axially thereof with the opening in one battle-means located at the opposite end from that in adjacent b'aflle-means whereby the interior of said shell is formed into a tortuous fluid-flow passage extending axially of said shell with one side of said passage contiguous to said warm-up chamber, a bundle oi open-ended tubes disposed in rows parallel to said baflle means and uniformly spaced apart between adjacent baflle means so as to establish a predetermined resistance to fluid flow through said tortuous shell passage, and means spacing apart adjacent rows of said tubes between at least one pair of adjacent bafiles a distance greater than the otherwise uniform spacing of said rows of tubes whereby the resistance to fluid flow between two adjacent rows of said tubes intermediate said battle-means and parallel thereto is less than that established by said uniform spacing of said tubes between adjacent baflies said means defining said warm-up chamber having apertures formed therein in registration with the more-than-uniformly spaced tubes effected by said spacing means whereby fluid from said warm-up chamber defining-means is" admitted directly to the space between said rows of tubes.

JOE C. SHAW. WILLIAM J. SCHLAPMAN.

REFERENCES CITED UNITED STATES PATENTS the Number Name Date 1,992,796 Young et al. Feb. 26, 1935 2,159,468 Young et al. May 23, 1939 2,222,496 Belaieff et al Nov. 19, 1940 2,270,864 Blais Jan. 27, 1942 05 2,288,599 Ramsaur July 7, 1942 2,307,300 Ramsaur Jan. 5, 1943 2,343,868 Dykeman et al Mar. 14, 1944 2,352,704 Garner July 4, 1944 2,376,198 Shaw May 15, 1945 7 2,406,203 Cruzan et al Aug. 20', 1946 2,449,922 Andersen Sept. 21, 1948 FOREIGN PATENTS Number Country Date 545,959 Great Britain June 19, 1942 

